This invention relates to an image reading method and apparatus that are used to read images recorded (photographed) on a photographic film photoelectrically. More specifically, the invention relates to an image reading method and apparatus having higher capability of detecting a scratch, a foreign matter such as dirt or dust and so forth that exist on the film, thereby obtaining image data in which the detected scratch and foreign matter have been corrected.
Heretofore, the images recorded on photographic films such as negative films and reversal films (which are hereinafter referred to simply as xe2x80x9cfilmsxe2x80x9d) have been commonly printed on light-sensitive materials (photographic paper) by means of direct (analog) exposure in which the film image is projected onto the light-sensitive material to achieve its areal exposure.
A new technology has recently been introduced and this is a printer that relies upon digital exposure. Briefly, the image recorded on a film is read photoelectrically, converted to digital signals and subjected to various image processing schemes to produce image data for recording purposes; recording light that has been modulated in accordance with the image data is used to scan and expose a light-sensitive material to record a latent image, which is subsequently developed to produce a (finished) print. The printer operating on this principle has been commercialized as a digital photoprinter.
In the digital photoprinter, images are converted to digital image data which are processed to determine the exposing conditions for printing. Hence, the digital photoprinter is capable of performing effective image processing operations such as the correction of washed-out highlights or flat shadows due to the taking of pictures with back light or an electronic flash, sharpening and the correction of color or density failure and this enables the production of high-quality prints that have been impossible to attain by the conventional direct exposure technique. In addition, not only the assembling of plural images and the dividing of a single image but also the compositing of characters on image can be performed by processing the image data and, as a result, prints can be output after various editing and/or processing operations have been performed in accordance with specific uses.
Outputting images as prints (photographs) is not the sole capability of the digital photoprinter; the image data can be supplied into a computer or the like and stored in recording media such as a floppy disk; hence, the image data can be put to various non-photographic uses.
Having these features, the digital photoprinter is basically composed of an image input machine having a scanner (image reading apparatus) that reads the image on a film photoelectrically and an image processing apparatus that processes the image read with the scanner to produce output image data (exposing conditions) as well as an image output machine having a printer (image recording apparatus) that scan exposes a light-sensitive material in accordance with the image data output from the image input machine to record a latent image and a processor (developing apparatus) that performs development and other necessary processing on the exposed light-sensitive material to produce a print.
In the scanner, reading light issuing from a light source is allowed to be incident on a film, from which projected light bearing the image recorded on the film is produced and focused by an imaging lens to form a sharp image on an image sensor such as a CCD sensor; the image is then read by photoelectric conversion and sent to the image processing apparatus as image data for the film (i.e., image data signals) after being optionally subjected to various image processing schemes.
In the images processing apparatus, image processing conditions are set on the basis of the image data read with the scanner and image processing as determined by the thus set conditions is performed on the read image data and the resulting output image data for image recording (i.e., exposing conditions) are sent to the printer.
In the printer, if it is of a type that relies upon exposure by scanning with an optical beam, the latter is modulate din accordance with the image data sent from the image processing apparatus and deflected in a main scanning direction as the light-sensitive material is transported in an auxiliary scanning direction perpendicular to the main scanning direction, whereby a latent image is formed as the result of exposure (printing) of the light-sensitive material with the image bearing optical beam. Development and other processing as determined by the light-sensitive material are then performed to produce a print (photograph) reproducing the image that was recorded on the film.
It is natural that the original of a print to be produced or the film must be in a good condition in order to reproduce a high-quality image thereon.
The film is transported in a camera for photographing, a developing apparatus for development and a scanner for reading (printing). During the transport, the surfaces of the film are in sliding contact with support members of the camera, the developing apparatus or the scanner. As a result, scratches may be often caused on both sides of the film. Further, the film is very often treated in an ordinary environment in which any particular air cleaning is not performed. Hence, any foreign matter such as dirt or dust is likely to adhere to the surfaces thereof.
As described above, when reading the image recorded on the film in the scanner, reading light is allowed to be incident on the film to produce projected light that is read photoelectrically with the CCD sensor. In this process, any foreign matter adhered to the film surfaces or any damage thereof blocks out or diffuses the reading light (projected light) to thereby reduce the quantity of light. In case of a deep scratch, the quantity of transmitted light of the reading light is increased to the contrary, whereby the light intensity of the projected light incident on the CCD sensor becomes inappropriate and no longer corresponds to the image on the film.
As a result, a high quality image cannot be obtained, since the foreign matter or the scratch is reproduced like a shadow on the obtained image and the peripheral image portion of the scratch looks blurred on the obtained image.
A primary object of the present invention is to solve the prior art problems by providing an image reading method that is applied to the aforementioned digital photoprinter and that is capable of surely detecting a foreign matter such as dirt or dust adhered to the film and a scratch thereon as will as an image reading apparatus used in the digital photoprinter for implementing the above method.
Another object of the invention is to provide an image reading method and apparatus that ensure correction of the detected scratch and foreign matter thereby obtaining image data capable of reproducing a high quality image without deterioration due to the scratch and the foreign matter, as in the primary object of the invention described above.
In order to achieve the above objects, the present invention provides an image reading method comprising the steps of:
allowing reading light to be incident on and pass through a film to obtain projected light; and
reading the thus obtained projected light photoelectrically to perform reading of an image recorded on the film,
wherein at least one of a scratch and a foreign matter on the film is detected based on at least two reading results obtained by reading the same image independently with at least two types of reading light in different states of diffusion.
Preferably, the at least two types of reading light in the different states of diffusion include a type of reading light in a state near to parallel light and another type of reading light in a state near to perfectly diffused light.
Preferably, the scratch and the foreign matter are a scratch and a foreign matter in the image or an image area recorded on the film.
Preferably, the at least two types of reading light in the different states of diffusion include reading types of light that are issued from at least two light sources and in which the states of diffusion are different from each other.
Preferably, the at least two types of reading light in the different states of diffusion include a type of reading light issued from a light source and another type of reading light obtained by diffusing the type of reading light issued from the light source by means of a diffusing device so that the states of diffusion are different from each other.
Preferably, the at least two reading results are obtained by using a plurality of sensors having different spectral sensitivities in accordance with the states of diffusion of the at least two types of reading light in the different states of diffusion.
The present invention also provides an image reading apparatus which allows reading light to be incident on and pass through a film to obtain projected light and reads the thus obtained projected light photoelectrically to perform reading of an image recorded on the film, comprising:
a light-issuing device for allowing at least two types of reading light in different states of diffusion to be incident on the film;
an image reading device for reading photoelectrically the projected light bearing the image recorded on the film as obtained from the at least two types of reading light in the different states of diffusion that have been issued from the light-issuing device and passed through the film; and
a detecting device for detecting at least one of a scratch and a foreign matter on the film based on at least two reading results obtained by reading the same image independently with the at least two types of reading light in the different states of diffusion by means of the image reading device.
Preferably, the light-issuing device includes at least two light sources that issue the at least two types of reading light in the different states of diffusion, respectively.
Preferably, the light-issuing device includes a light source issuing a type of reading light and a changing device for changing the type of reading light issued from the light source so that said states of diffusion of said type of reading light and another type of reading light being produced are different from each other.
Preferably, the image reading device has a plurality of sensors having different spectral sensitivities and the plurality of sensors having the corresponding spectral sensitivities are used in accordance with the states of diffusion of the at least two types of reading light in the different states of diffusion to obtain the at least two reading results.
Preferably, one of the plurality of sensors is a monochrome sensor.
Preferably, the image reading device obtains the at least two reading results by prescan for reading the image recorded on the film at low resolution.
Preferably, the detecting device uses the at least two reading results to detect, as the at least one of the scratch and the foreign matter, a region that has a difference between image data read with reading light of lower diffusion and image data read with reading light of higher diffusion in the at least two types of reading light in the different states of diffusion.
Preferably, the image reading apparatus further includes a deficient pixel correcting device for correcting, as deficient pixels, a region corresponding to the at least one of the scratch and the foreign matter detected by the detecting device.
Preferably, the deficient pixel correcting device performs correction using surrounding image data of the deficient pixels.
Preferably, the deficient pixel correcting device performs at least one of a method of substituting image data of the deficient pixels by the surrounding image data of the deficient pixels, a method of substituting the image data of the deficient pixels by image data calculated by interpolation with the surrounding image data of the deficient pixels, and a method of using, as the image data of the deficient pixels, image data read with reading light of higher state of diffusion in the at least two types of reading light in the different states of diffusion.